One of the tower ladders at work had this several years ago. For OUR applications, the members found it to be more cumbersome than practical. We're generally able to get our extrication pieces close enough to the vehicles that we can use the tools on the reels.

Probably the biggest drawback for our guys was the weight.

Keep in mind, this particular rig was keeping all of their tools on two carts - nothing was mounted to the apparatus. A cart with a redundant system would have been fine, but not as the primary set of tools.

HRT Cart

EJ.
The cart you see in the pic is standard issue to FDNY ladder companies. Like Box alarm mentions the weight is a big factor in lugging the tool around. The handtruck itself is almost 50 lbs.
In my company I fabricated a cart from a simple furniture dolley. (The handtruck wouldnt fit in the compt) We secured the power unit on the base and mounted two pieces of pipe to hold the spreaders. Kept it simple and it worked pretty good.